Paper by Anno Graser, M.D., and Christoph R. Becker, M.D., Department of Clinical Radiology,
University of Munich, Grosshadern Campus, Munich, Germany
In the colon and rectum, the vast majority of cancers develop very slowly, approximately over a period of 10 to 15 years, from benign precursor lesions. These lesions, so-called polyps, can undergo malignant transformations based on the adenoma-carcinoma sequence. Therefore, the resection of polyps reduces colorectal cancer mortality by over 90 percent.
Computed tomographic colonography (CTC), also referred to as virtual colonoscopy (VC), shows a promising potential for colorectal cancer (CRC) screening due to its high sensitivity and specificity in the detection of colorectal polyps [1, 2].
Over the last months, the ongoing discussion about how to perform screening for colorectal cancer has intensified. In Germany, as well as in the United States, recommendations have been made that every person over 55 years of age undergo a CRC screening with colonoscopy.
Over the last ten years, technical advances in CT scanners, as well as post-processing software, have led to increased diagnostic performance of CTC. After the introduction of four-detector row scanners in 1998, the technique of virtual colonoscopy has improved tremendously. A recent multicenter study showed a very high sensitivity in the detection of colrectal polyps ; two studies published shortly afterward raised doubt as to whether these results are reproducible